Production of aluminum chloride free from iron



Patented Dec. 22, 1931 UNITED STATES Jomumns Baonn, orLonwIosnAI'EN-oN-rminmnn 61mm, assrenoa'ror (1. rmmrmnosrnmArc'rInnansnnnsonaiyr,I oramnnnoa'r onmmm onn MANY, A CORPORATION OFGERMANY rnonuc'rron or ALUMINUM mammals raontiraori i J:

No Drawing. Application filed August The present invention relates tothe production of aluminum chloride free or practically free from ironand in particular iron chloride. 7

In the manufacture and production of anhydrous aluminum chloride fromclay, bauxite, or other raw materials by the usual proc-.

esses, in consequence of the natural iron content of the initialmaterial, aluminum chloride contaminated with iron chloride is obtained,which cannot be obtained in a pure state by fractional condensation atdiffer-; ent temperatures, because the chlorides partially dissolve onein another. 7

In order to purify t e aluminum chloride from its iron content it hasbeen proposed to pass the chloride mixture, in the form of vapour, overmetallic aluminum or iron or over base metals, such as sodium, magnesiumand the like. This process has the objection that the chloride mixtureto be'purified must be passed over the metal chosen or through a meltthereof with the complete exclusion of ases having an oxidizing action.When pro ucing aluminum chloride from raw materials containing oxideswith the aid of chlorine and carbonaceous re agents, the vapours leavingthe reaction furnace always contain carbon dioxide. If such aluminumchloride vapour containing carbon dioxide is passed directly over ironor aluminum turnings or through molten aluminum for the purpose ofurification, at the taining vaporized in an iron temperature necessarythe reaction:

FeCl -l-Al=AlCl +Fe, or 2FeCl Fe 3FeCl oxidation of the metallicaluminum or iron by the carbon dioxide occurs, and themetals thusoxidized on the surface can no longer efiect the reducing action.

Thus this purification process can onlybe employed when the aluminumchloride vapour, which on leaving. the reaction furnace is already atthe temperature necessary for the reaction for the removal of iron, iscooled, and condensed, and the condensed aluminum chloride containingiron is vaporized again.

I have. now d that this difficulty is foun avoided, and the crudechloride is obtained ducing thereto. 7

5,1929, Seria1i1ifo.388, 79 1, and in aer anyau as erz, azai in a pureor practicall eration, hybringirig t 'e aluminum chloride vapour, whichcontains'irontnichloride, into contact with moltenlead. At temperaturesabove melting point lead reacts; with the iron trichloride. (FeGl inthe. aluminum? of diflicultly chloride, with" the formation volatileiron dichloride (FeClQ and lead chloride? and a pureor practically purealuminumchlorideisolitained; In consequence of the fact that lead is notreadily oxidized, aluminum chloride vapour containing carbon'dioxide can.be employed directly for the purification without previous treatment,without injury to the activityof thelead.

Lilhe process inaaccordance with the present'zinvention is preferablycarried outby' pass n the aluminum chloride vapourwhich is to r epurified Linto themo1ten lead by means "of an inlet beneath the'surface,. and thencondensing thevapouriafter it has bubpure one op bledthrough the lead bath. The chlorides formed by the'reaction :(irondichloride and lead chloride) float on the surface of the mola tenlead,andloanbeskiinmed oif, or can be dissolved out with water, fromtime to time.

The following examples will further illustrate how my invention may becarried out in practice, but the invention is not restricted Example 1kilograms of aluminumchloride con- 6.54 per cent of ferric chloride areEwampl? Aluminum chloridecontaining 2.4 per cent of ferric chlorideisproduoed by the interaction of kaoline, carbon monoxide and chlorine.The resulting gas and vapour mixture vessel of 200 litres capaoity bymeans of a slow current of nitrogen. The resulting gas containingalittle chlorine and carbon monoxide in addition to aluminum chloride andcarbon dioxide is passed directly throu h a bath of fused leadelectrically heated to a out 5 400 C. Ferrous chloride andsmallquantities of lead chloride are formed. Preferably the lead bath isstirred in order to prevent said chlorides from forming a crust on thesurface of the bath, which would obstructthe passage of the aluminumchloride vapours which are condensed by cooling. The resulting productcontains. less than 0.1 per cent of ferric chloride.

What I claim is;

1. The process of producing pure aluminum ichloride which comprisescontacting vapours of aluminum chloride 1condtaminatedwith'ferricchloride, with fused 2. The processof producing substantially purealuminum chloride which comprises contacting the gas mixture containingaluminum'chloride contaminated' with ferric chloride resulting from theroduction of aluminum chloride, with fuses lead.

3.;T e process of producing substantially pure aluminum chloride whichcom rises contacting vapours of aluminum ch oride contaminated withferric chloride, with fused lead at about400. C.

he process of producing substantially pure aluminum chloride whichcomprises contactingv the gas mixture containing aluminumchloride'contaminated with ferric chlov ride resultin from theproduction of aluminum' chlori 400? C; i p a In testimony whereof I havehereunto set my hand. I

JOHANNES BRODE.

e, with fused lead at about the substantially

